Central Bureau for Astronomical Telegrams
IAUC 5759: 1993J; GRB J0444-0700
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Circular No. 5759
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
SUPERNOVA 1993J IN NGC 3031
S. D. Van Dyk and K. W. Weiler, Naval Research Laboratory; M.
P. Rupen and R. A. Sramek, National Radio Astronomy Observatory;
and N. Panagia, Space Telescope Science Institute, report: "New
observations of SN 1993J made on Apr. 8.33 UT with the Very Large
Array in 'B' configuration show that the source is now detectable
in at least three frequency bands. This confirms the first weak
detection (IAUC 5752) of the supernova at 1.3 cm (22.5 GHz) on Apr.
2.30. The source has now risen dramatically in flux density at 1.3
cm to 18.94 +/- 0.20 mJy at R.A. = 9h51m19s.042, Decl. =
+69 15'26".45 (equinox 1950.0; +/- 0".2 in each coordinate), in
excellent agreement with the previously reported position. The radio
position for SN 1993J, compared with the radio position for the
nucleus of NGC 3031 given on IAUC 5752, yields an offset for the
supernova of 44".0 west, 161".8 south. The supernova is also detected
at 2.0 cm (14.9 GHz) with flux density 8.04 +/- 0.18 mJy, confirming
the previous detection made at this wavelength by Pooley and
Green (IAUC 5751), and at 3.6 cm (8.4 GHz) with flux density 0.74
+/- 0.05 mJy. The radio spectrum of the supernova is optically
thick, as is expected at this time. Comparison with the type-II
linear radio supernovae 1979C and 1980K shows that SN 1993J has
turned on in the radio significantly earlier than the two previous
supernovae. This implies that there is less absorption external to
the radio emitting source for SN 1993J and therefore, from
modelling, that the progenitor of SN 1993J was probably less massive
than the progenitors of the other two radio supernovae, assuming
that SN 1993J is type-II/linear as were SNe 1979C and 1980K; if the
supernova is type-II/plateau, then its behavior in the radio is
unpredictable, since a supernova with this subtype has never been
previously detected at radio wavelengths. Radio monitoring is
continuing on a nearly daily basis at these and other wavelengths in
order to follow the supernova's rapidly changing behavior."
GRB J0444-0700
S. Brandt, N. Lund, and A. J. Castro-Tirado, Danish Space
Research Institute, report: "A bright gamma-ray burst was detected by
the WATCH wide-field instrument on EURECA on Apr. 10.59661 UT. The
burst was located at R.A. = 4h44m, Decl. = -7 00' (equinox 2000.0).
The radius of the error circle is 45'. Follow-up observations in
the optical and radio are encouraged."
1993 April 12 (5759) Daniel W. E. Green
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